In order to improve properties of various base materials, it has been attempted to form a vapor deposited film on their surfaces by a plasma CVD method. In the field of packing materials, it is a known practice to improve gas shut-off property by forming a vapor deposited film on the plastic base materials such as containers by the plasma CVD method. For example, there has been known a method of forming a vapor deposited film of a silicon oxide on the surfaces of the plastic containers such as PET bottles by the plasma CVD method by using a mixed gas of an organosilicon compound and oxygen as a reaction gas, in order to improve gas-barrier property.
The above silicon oxide film is basically highly rigid and brittle. When deposited on a plastic substrate, the silicon oxide film poorly follows the deformation of the plastic substrate, easily peels off and lacks closely adhering property. Therefore, it becomes necessary to deposit a film of the silicon oxide after a closely adhering layer is formed on the surface of the plastic substrate. For example, patent document 1 proposes forming a closely adhering layer rich in carbon element (C) on the surface of a plastic substrate by conducting the plasma CVD by using a reaction gas having a high organosilicon compound concentration or by employing a low-output condition prior to depositing a film of silicon oxide.
Study has also been conducted extensively concerning depositing the films other than depositing the silicon oxide. For example, a patent document 2 is proposing the formation of a hydrocarbon type vapor deposited film comprising amorphous carbon as a chief component by the plasma CVD on the surfaces of the plastic containers. Moreover, patent document 3 is proposing the formation of a vapor deposited film on the inner surface of a plastic container by the plasma CVD method, the vapor deposited film having a film structure in which a diamond-like carbon film (hydrocarbon vapor deposited film) is formed on the silicon oxide film.
Patent document 1: JP-A-2005-97678
Patent document 2: JP-A-2006-131306
Patent document 3: JP-A-2006-89073